Free piston engine fuel control



Nov. 2l, 1950 1 J, GARDAY 2,531,331

FREE PISTON ENGINE FUEL CONTROL Filed Oct. 22, 1947 3 Sheets-Sheet 1 NW 21 1950 L. J. GARDAY 2,531,331

FREE PISTON ENGINE FUEL CONTROL Filed Oct. 22, 1947 3 Sheets-Sheet 2 Ju FE 7 `\63 /92 )a7 M 6fl f/r /J; f 1% 2 95 J3 )32j ze /s 9) NOV. 21, 1950 L, J, GARDAY FREE PISTQN ENGINE FUEL CONTROL 3 Sheets-Sheet Filed Oct. 22, 1947 Patented Nov. 21, 1950 MNITED ,sien

STTES PATENT Y OFFIC 2,531,331 FREE rrs'roN ENGINE FUEL coN'raor.

lLouis J. Garday, Glenview, Ill., assigner, by mesne assignments, to Louis G. Simmons, Chicago, Ill.

. il? Claims. i

This invention relates to gas generating apparatus operating with periodic injections of fuel and to fuel injection apparatus therefor, more particularly to such gas generating apparatus oi' the so-cal1ed free piston type. and it is an object of the invention to provide improved apparatus of this character.

It is a further object of the invention to provide improved fuel injector control means for apparatus of the character indicated.

It is a further object of the invention to provide improved apparatus of the character indicated wherein the fuel injection means supplies a positively metered amount of fuel from a high pressure source.

It is a further object of the invention to provide apparatus of the character indicated embodying improved means for controlling the timing of fuel injections and improved means for controlling the volume of fuel injected.

In carrying out the invention in one form, gas generating apparatus is provided comprising a combustion chamber for supplying gas under pressure, a chamber for receiving the gas from the combustion chamber, a fuel measuring chamher, and a piston movable therein under the tial areas exposed to the fuel under pressure are associated with the fuel measuring chamber for preventing the election of fuel therefrom, and

timing means controlled by the generating apparatus are adapted to relieve the fue] pressure from one of the differential areas whereby the valve means open and the piston moves to produce fuel injection. Means responsive to the pressure in the gas receiving chamber cooperate with the timing means for varying the timing if the pressure relieving and governing means For determining the capacity of the fuel measuring chamber are provided together with means responsive to a condition of the generating apparatus operation for altering the fuel measuring capacity determined by the governing means.

For a more complete understanding of the invention, reference should now be had to the accompanying drawings in which:

Figure 1 is a diagrammatic view of gas generating apparatus embodying the invention;

Fig. 2 is a detailed fragmentary side view partially broken away and on a larger scale of the apparatus shown in Fig. l;

Fig. 3 is a top plan view partially broken away of the apparatus shown in Fig. 2;

Fig. 4 is a fragmentary end view partially in section and partially broken away taken substantially along lines 4 4 of Fig. 2, and

Fig. 5 is a sectional view partially broken away taken substantially along lines 5-5 of Fig. 3.

Referring to Fig. 1 of the drawings, the lnvention diagrammatically shown as embodied in gas generating apparatus of the so-called free piston type operating upon the principle of compression ignition, the gas generating apparatus including a combined motor and compressor unit Ill and fuel injecting apparatus I I, together with its control means. Y

Motor compressor unit il) includes a motor cylinder l2, compressor cylinders I3 and il axially spa-ced at each end thereof, and pistons l5 and i6. Piston I5 comprises a motor piston portion Il movable within motor cylinder I2, and a compressor piston portion I8 attached to, and preferably integral with piston portion l1, movable in compressor cylinder Il. Similar to plston l5, piston IB comprises a motor piston portion i9 movable in motor cylinder I2,l and a compressor cylinder portion 2l attached to, and preferably integral with, motor piston portion i9, movable in compressor cylinder I3. Motor piston portions il and I9 face each other within motor cylinder I2 and define a combustion chamber between their end surfaces into which fuel is adapted to be injected by an injection nozzle 22.

Extending axially from compressor cylinder it on the opposite side thereof from motor cylinder l2 is a cylinder 23 in which is movable a piston portion 2t forming part of piston l5 and axial therewith. Similarly, a cylinder 25 extends axially from cylinder i3 on the opposite side thereof from motor cylinder l2 in which is movable a piston portion 26 forming part of piston i8 and axial therewith. In the position shown in Fig. l, motor piston portions I'I and I9 are virtually in the fuel ignition positions and compresser pistons I8 and 2l are in the position of havinglled the compressor cylinders with air. At the same time, piston portions 24 and 26 are at their extreme inward positions in closed cylin-fers 23 and 25, thereby forming chambers containing air. When through the process of combustion motor piston portions l1 and i9 are orced outwardly to the scavenging position, the

ncompressor cylinder portions i8 and 2l compress the air within the cylinders i4 and i3 respectively, forcing the compressed air into a receiver 2l and also forcing piston portions 24 and 26 respectively into cylinders 23 and 25 to compress the air therein which serves to return pistons I8 and I6 to the combustionv positions.

Intake valves 28 and 29 and discharge valves 3| and 32 are associated respectively with compressor'cylinders I4 and I3, the discharge valves being arranged within conduits connected with receiver 21 whereby the air compressed within cylinders I4 and I3 flows into receiver 21 on the compression or power stroke, but is prevented from flowing backwardly into the compressor cylinders during the intake stroke.

A duct or conduit 33 leads from receiver 21 to a series of circumferentially disposed air intake ports 34 in one end of combustion cylinder I2, at the other end of lwhich there is a series of circumferentially disposed exhaust ports 35 communicating with a duct 36 leading to an exhaust gas receiver 31. Piston portions I1 and I9 being shown adjacent each other, ports 34 and 35 are covered up, but when the pistons are in their outward positions, piston portions I1 and I9 uncover respectively ports 35 and 34 thereby forming a complete passageway from receiver 21 through duct 33, ports 34, combustion cylinder I2, ports 35, and duct 36 to exhaust receiver 31. Consequently the compressed air in receiver 21 flows through cylinder I2 to receiver 31 thereby scavenging the combustion chamber and at the same time supplying compressed air to receiver 31 for use in a load such as a turbine, for example. The exhaust ports 35 preferably are arranged to be opened by piston I1 slightly before piston I9 opens ports 34 in order that the combustion gases under high pressure in cylinder I3 may now into receiver 31 to reduce the pressure in cylinder l2 before the compressed air from receiver 21 flows therethrough. Accordingly, as a result of the engine operation, exhaust gas receiver 31 receives the exhaust gases resulting from the combustion of fuel as well as the air compressed in cylinders I3 and I4.

Pistons I5 and I6 are connected to each other through synchronizing racks 38 and 39 engaging with a gear 4|. Consequently, the traveling free pistons are constrained to move with each other. If either of the pistons should tend to stick in its to'and fro movements, a force is exerted on gear 4| tending to move it longitudinally, this tendency being used to stop engine l to prevent damage thereto. as will be described subsequently in this specification. Also. if the pistons tend to overtravel at the scavenging end of their stroke, mechanism to be described will be set into operation to reduce the amount of fuel supplied to the engine thereby reducing the amount of fuel supplied to the engine thereby reducing the length of piston travel.

' Fuel is supplied from a high pressure source F in definite metered quantities by virtue'of the fuel injector proper 42 forming part of injecting apparatus the injector being connected to nozzle 22 through conduit 15 and to source F through conduit 14. Initiating operation of injector 42 is brought about by timing mechanism 43, also forming part of apparatus the timing mechanism including a timing plunger 53 4 amount of fuel injected by injector 42 is associated therewith and includes a lever 49 for producing a normal governor setting, the governor being adapted to have its setting reduced toward zero when pistons I and I6 overtravel at the scavenging end. and is adapted to have its setting reduced to zero when either of the pistons tends to stick in its to and fro movements. Reduction in the governor setting is effected by impulses of fuel under pressure through conduits 5I or 52 from s source S of relatively low fuel pressure, the fuel and a rocking cam 44 which is oscillated back and d Y forth by the to and fro movements of the synchronizing racks. A pressure responsive element 45 is associated with timing mechanism 43 and is connected to exhaust receiver 31 through a duct 46 whereby the initial setting of the timing mechanism may be varied (i. e., the timing regulated) in accordance with the pressure in receiver 31. A governor mechanism 46 impulses through conduit 5| being eifected by excessive movements of rocking cam 44, while the fuel impulses through conduit 52 are supplied when longitudinal movements of gear 4I occur.

The operation of the various individual elements illustrated in Fig. l is completely automatic. That is. when the pistons are in combustion position as shown, fuel injection is initiated by rocking cam 44, in one position through its lobe |26, moving the timing plunger 53 to a position connecting conduits |08, |I1 to the exterior and if, as a result of the combustion. the pistons overtravel at the scavenging end. a lobe |64 lon the rocking cam in its other position effects connection of conduit 5| to the source S thereby causing governor 48 to reduce the amount of fuel injected. Furthermore, if as a result of operation the pressure in receiver 31 should change, the pressure responsive element 45 responds to change the relative rotational position of plunger 53 to vary the fuel injection timing.

Referring to Fig. 2, in which the same reference characters are used for corresponding parte as in Fig. l, the fuel injecting apparatus is shown attached to a rigid member 56 which may form part of a gas generator by means of bolts l1. Rigidly associated with member 56 are the guides 58 and 58 within which the synchronizing racks 38 and 39 are adapted to slide. Supported between guides 58 and 59 is an assembly 6| including a. pair of yoke members 62 and 63 held together by means of bolts 64 to support the gear 4| upon a shaft 65. At each end of assembly 6| there is a housing 66 having an opening through which the flanged plunger 61 projects, a spring 68 being provided in the housing for maintaining the plunger in its outward position. Also rigidly attached between guides 58 and 59 is an abutment 69 into which the stop 1| is adjustably threaded, the stop being adjusted to directly abut plunger61. At the other end of assembly 6| there is an abutment similar to 69 and a stop similar to 1| so that assembly 6|, including the gear 4|, is normally stationarily held between abutments 69. Assembly 6|, however, is slidable between the inner surfaces of guides 58 and 59. Consequent- 1y, whenever either of the synchronizing racks fail to move properly (one of the piston tends to stick, for example), movement of the other rack tends to move gear 4|, and consequently assembly 6I, longitudinally against stop 1|. Small movements of assembly 6| open a safety shutoff valve 12 (Fig. l) to completely cut off the engine fuel. Normal movements of synchronizing racks 38 and 39 merely produce'rotation of gear 4|, thereby causing rotation of a gear 13 attached to shaft and meshing with corresponding teeth on rocker cam 44 to produce fuel injections and piston overtravel regulation.

The apparatus Il, including injector 42, fuel metering governor 48, timing mechanism 43, timing regulator 45, and related elements are embodied in a relatively unitary structure including adapted to vary the 76 a body member 16 shown in Figs. 2, 3, 4 and 5.

Considering rst the fuel injector proper, and referring to Fig. 3, body 16 is provided with a pair of inwardly extending bores one of which is adapted to contain a piston guide 11 and the other of which is adapted to contain a par of serially spaced valve guides 18 and 19.' Within piston guide 11 there is a piston 8| including a reduced portion 82 at one end which forms, together with guide 11, a fuel ejection chamber 83, a spring 84| be ng arranged as shown to bias the piston toward its right hand position. A piston stop 85 is threaded in a piston stop guide 86 which is abutted by the shaft guide 81, the shaft guide being held in position and thereby holding the abutting elements within this bore of body 16 in position by means of a retainer sleeve 88 held to the body by bolts 89. A shaft 9| is rotatable within shaft guide 81 and is splined to piston stop 85 so that by rotating shaft 9| the position of the piston stop may be varied to determine the position of piston 8| within guide 11 and consequently to determine the capacity of ejection chamber 88. Shaft 9| is rotated by virtue of a gear 9 2 keyed thereto, the gear being engaged by a toothed rack 93 slidable in a bore within body 18, as is shown best in Fig. 5.

A series of passageways extend through piston stop guide 88, the passageways communicating with a passageway or duct 18 and hence with a central bore or chamber 95 connected to the high pressure source of fuel F. Thus, high fuel pressure is continually being exerted against the base of piston 8| tending to force it to fuel ejection position. Chamber 95 forms a substantially uniform supply of high pressure fuel necessary for optimum operation at all speeds and loads inasmuch as the source F may be some distance away and connected to chamber 95 through several feet of conduit. Piston 8| includes a series of grooves around its circumference, as shown, one or more of which communicate with radial holes through piston guide 11 and thence with a conduit 98 whereby fuel leakage past the piston and into the other mechanism is prevented.

Valve guides 18 and 19 are spaced from each other by a spacer 98. and passageways 91 and 98 respectively extend therethrough, the valve guides also being provided with centrally extending bores in which valve bodes 99 and |8| are adapted to move. The right end of valve guide 19 abuts against a spacer |82 having angularly extending passageways communicating with passageway 98 and with discharge chamber 88 through a bore |83. Spacer 98 at the left end of valve guide 19 includes a central bore and angularly extending passageways, the central bore being adapted to be closed by the left end of valve iti. The angula'r passageways in spacer 98 communicate with passageway 91 and thence through a central passageway in spacer |88, a nut |85, and conduit to injection nozzle 22. The left end of valve 99 covers the passageway through spacer |84 and the left end of valve |8| closes the passageway through spacer' 96 to prevent the flow of fuel to the injection nozzle except when desired, When valves 99 and 18| are held away from spacers |84 and 96, there is a continuous passageway from the injection nozzle through passageways 91 and 98 and bore |83 to discharge chamber 83.

The right end of valve guide 19 is enlarged to form a bore within which the head of valve |8l, a spring |86, and a valve stop |81 are disposed, the spring |06 urging valve |8| against spaced 96 and valve stop |81 against spacer |82. The bore containing valve stop |81 is connected with a passageway |88 which is connected with radial passageways |89 and passageway or duct iii in timing valve guide H2 (with parts in the position shown in Fig. 3) and hence with chamber 95 (source F). Consequently the fuel in chamber lls the various passageways and exerts high pressure against the head of valve |8| and thereby urges this valve to close the passageways through spacer 96. Spacer |82 has a central bore adapted to be closed by a reloading valve ||3 biased to a closed position by spring H4, the central bore being in communication with a longitudinal passageway as well as radial passageways in stop |81, and when reloading valve |3 is open there is a continuous passageway from source F to discharge chamber 83. Since the fuel in chamber 95 exerts its pressure against the base of piston 8 the fuel pressure on each side of piston 8| is the same, thereby allowing spring 3l to return piston 8| against the stop 85.

The right end of valve guide 18 is somewhat enlarged to form a bore containing the head of valve 99, a spring H5 and a valve stop i9, spring i5 urging valve 99 against spacer |84. The bore containing valve stop H6 is connected through passageway i i1 with radial passageways |89, passageway Hi, and source F. Accordingly, with parts in the position shown in Fig. 3, high fuel pressure is exerted against the head of valve 99 thereby holding this valve in its closed position.

The left ends of valves 99 and |8| are reduced in area and are very nely nished so that when the valves abut against spacers 98 and |84 iuid is unable to pass between the abutting surfaces. As a result, when the valves are closed the pressure of fuel in passageways 91 and 98 is exerted against only that portion of the areas on the valve ends which do not abut the spacers. However, the fuel pressure in passageways |88 and ||1 exerts pressure against the full crosssectional area of the valves at their right ends. Thus, even though high fuel pressure may be exerted in passageway 98, it is exerted against a smaller area of the valve than the fuel pressure in passageway |88 and consequently valve |8| maintains a closed position when full pressure is applied to vboth ends thereof. When valve |8| is closed, the fuel from discharge chamber 88 and passageway 98 cannot pass through the bores in spacer 96 and into passageway 91. Whatever fuel pressure may be exerted against the reduced area at the left end of valve 99 through passageway 91 and tending to open the valve is opposed by the high fuel pressure in passageway i1 being exerted against the full cross-sectional area of the valve body. Therefore valve 99 also maintains a closed position normally. When, however, valves 99 and |8| are open, the high fuel pressure being exerted against the base of piston 8| causes movement thereof to eject fuel through a continuous passageway extending from discharge chamber 83 to injection nozzle 22. Injection nozzle 22 includes a spring biased, closed needle valve which is lifted off its seat by the injection pressure. The nozzle spring has a spring constant such that the pressure necessary to open it is greater than the closing pressure of valves 99 and |8| which, accordingly, stay open until complete fuel ejection has occurred through the nozzle.

The initiation of fuel ejection is effected by the timing mechanism 43 also embodied within structure il. The timing plunger 53 is slidable within a central bore in guide l2 and includes-a circumferential groove i|8 and a slot. ||9 extending angularly around the circumference thereof, the angular slot ||9 being connected with a central passageway in the plunger which is connected to the exterior of the structure. In the position shown in Fig. 3, the circumferential groove ||8 connects the passageway to passageways v|08 and ||1 thereby supplying high pressure fuel to the heads of the valves. However. when plunger 53 is moved toward the right hand position, the radial passageways |09 are rst closed by the full diameter of plunger 53 and thereafter when angular slot ||9 comes into registry with radial passageways |09 the high fuel pressure existing in passageways |08 and ||1 is relieved by the fuel therein flowing out through the longitudinal bore in plunger 53. Accordingly in this position there is low pressure being'exerted against the heads of valves 99 and |0|, and since the high pressure of the fuel in discharge chamber 83 is being exerted against the left end of valve this valve opens against the bias of spring |06'. Then the high pressure in chamber 83 (caused by high` pressure being exerted against the base of piston 8| through passageway 14) isexerted through passageway 91 against the left end of valve 99 and this valve opens against the bias of spring 5. (The phase of operation just discussed is illustrated diagrammatically in Fig. 1.) When timing plunger 53 moves toward its left hand position (after fuel imection) the angular slot moves away from radial passageways |09 thereby closing the relief passageway, and when the plunger has moved to the position shown in Fig. 3, passageway is again connected to passageways |08 and ||1, thereby exerting high pressure against the heads 0f valves 99 and |0|.

The pressure of fuel in passageways 91 and 98 and in discharge chamber `83 is low after fuel injection has occurred, thereby allowing the high pressure in passageways |08 and |1 with the aid of springs and |06 to close valves '99 and |0|. Since the pressure in discharge chamber 83 is also low, the high pressure in passageway |08 is exerted through the central passageway in valve stop |01 and lifts reloading valve ||3 off its seat. This equalizes the pressure on each s-de of piston 8| and permits spring 84 to move the piston against stop 85, thereby filling discharge chamber 83 with fuel. During the fuel ejection process when the pressure in passageway |08 is low, the high pressure fuel in discharge chamber 83 is exerted against reloading valve ||3, maintaining it in a tightly closed position.

The timing plunger 53 is connected to a collar |2| which is urged outwardly by a spring |22 (Figs. 2 and 3). Collar |2| abuts against the inside of a cup |23 including a semi-cylindrical bearing surface into which is received one end of theV rocker link |24. The other end of rocker link |24 is received in a correspondlng bearing surfrace at one end of tappet member |25 pivoted at its center to structure and 'adapted at its other end to contact a cam surface or lobe |26 on cam 44. Lobe |26 is so arranged that in the position shown in Fig. 2 valve plunger 53 is in the position shown in Fig. 3.

Movement of synchronizing racks 38 and 39 toward combustion pos'tion moves cam 44 by virtue of the gears 13 and 4| to the position shown in Fig. 1 where lobe |26 has moved tappet member |25, and consequently plunger 53, to a fuel ejecting position. Thus the movement of theA synchronizing racks through cam 44 and plunger'53 produces timing of the fuel injection which occurs whenever slot ||9 comes into communication with radial slots |09 and hence passageways |08 and ||1. Since slot ||9 extends angularly around the surface of plunger 53, the relative rotational position thereof determines the instant aty` which the angular slot comes into registry with slots |09. Consequently, variations in timing 'may be produced by rotating the valve plunger. This is accomplished by rotating the valve guide |21 from which extends a tongue |28 slidable in a slot in flange |29, flange |29 being part of a gear 3| engaging with a toothed rack |32 (see also Fig. 4). Toothed rack |32 moves in a vertical bore in body 16 and in so doing rotates the plunger 53, thereby varying the relative position of angular slot I9.

The final position of the timing plunger at fuel injection is determined by the final position of the synchronizing racks and hence by the power pistons at the combustion end of the stroke. A small time interval is needed for piston 8| to produce a complete fuel injection after initiation thereof by the registry of grooves ||9 and radial holes |09 due to the inertia of the fuel and parts and the friction present. This time delay is obtained by virtue of the spacing between circumferential slot ||8 and angular slot ||9. It will be seen that when slot ||9 and radial holes 09 register, this occurring for fuel injection irrespective of the final piston position, the timing plunger must move toward the left at least the distance between slot i9 and groove |8 to bring groove ||8 into communication with radial holes |09 and thereby stop fuel injection by the application of high pressure through passageways |08 and ||1 against the heads of valves 99 and |0|. Complete fuel injection will have occurred due to this time interval and is not hindered by the premature application of high pressure to the valve heads.

Body 18 includes two series of valves (one being valves 99 and |0|) and two injection pistons (one being piston 8|) (see Figs. 3 and 5), so that two fuel injections may be produced simultaneously. The dual portions of the apparatus are duplicates and only one has been described.

Governor mechanism 48 for varying the capac-v ity of fuel discharge chamber 83 forms part of the structure at the right end thereof. Re-

` ferring particularly to Fig. 5, the governor mechanism comprises a housing |30 including a bore Within which Ya piston |33 is adapted to move, one side of the piston'including teeth engaging with corresponding teeth on a gear |34. Gear |34 also engages with teeth on rack 93, and as a consequence, when piston |33 moves to and fro, rack 93 moves to and fro thereby rotating gear 92 to effect movement of piston stop 85 (Fig. 3) Piston |33 is hollow and abutting one end thereof is a spring |35, the other end of which abut: against a cross head |36 movable inside of the piston. Cross head |36 is pivotally attached to an arm 49 in turn pivotally mounted in housing |30 on a shaft |31 keyed to arm 49. Rotating shaft |31 moves arm 49 and consequently piston |33 to a desired position, an indicating arm |38 being attached to shaft |31 whereby the load may be indicated on a scale |39. The shaft |31 may be attached to controlling mechanism such as a throttle, for an example, not shown, by means of which the desired engine load may be set.

The right end of the bore in which piston |33 moves is closed by a by-pass needle body 4| to form a chamber |42. Fuel under pressure may be supplied to chamber |42 through conduits 5| assnssi i or 52 and opening |44, fuel flowing out of chamber 42 through a. conduit |45 as determined by the adjustable needle valve |48. In the position shown in Fig. 5, the governor is set for minimum or zero load. Consequently fuel under pressure flowing into chamber |42 will not aii'ect the position of piston |33. supposing, however, that the governor is set to a position, for example, fifty per cent load, in which event the right end of piston |93 will occupy a position shown by the broken line |41 and the fuel ejecting piston 8| (Fig. 1) will occupy an initial position so determined and discharge chamber 53 will contain an amount of fuel corresponding to ilfty per cent load. During operation, chamber |42 is filled with fuel at atmospheric pressure and, now, if fuel under pressure flows -ito chamber |42 this pressure will cause piston III to move, there'- by compressing spring |35, since arm 49 remains stationary as determined by the initial governor setting. The compressed spring, however, urges piston |33 toward broken line |41, thereby tending toyforce the oil in chamber |42 to flow out past needle valve 46. The needle valve may be adjusted to determine any particular rate of flow desired.

The unitary structure is more completely described and claimed inthe copending application Serial No. 781,427, filed October 22, 1947, entitled Fuel Pressure Operated Fuel Injector, to Louis J. Garday, and assigned to the same assignee as the present invention.

Bearing in mind the structure of the various elements described in connection with Figs. 2, 3, 4, and 5, the integrated operation thereof may be best understood by referring to Fig. 1. In.

Fig. 1 the pistons are in the combustion positions and consequently synchronizing racks 38 and 39 have approached each other thereby rotating gear 4| to move cam 44 into a position where lobe |26 has moved plunger 53 to a point where angular slot ||9 communicates with ducts |08 and In this position the fluid pressure against the rear of valves 99 and |0| has been relieved and the high pressure from discharge chamber B3 has lifted these valves oif their seats and injected fuel into the combustion chamber through conduit 'I5 and discharge nozzle 22. Combustion takes place as a result of the high temperature in the combustion chamber dueto the high compression of the air therein. As the combustion continues after fuel injection, pistons i5 and IB move outwardly effecting movement of synchronizing racks 38 and 39 away from each other and consequently rotating gearlli to move cam 44 and lobe |28 away from plunger 53. The plunger is then moved by spring |22 to a position where groove ||8 connects conduits |08, lil and to the high pressure source of fuel thereby refilling discharge chamber through valve H3 and closing valves 99 and |0| as has been described.

Since pistons I5 and i6 are free, in the sense that they do not have a fixed degree of movement, provision must be made to prevent the pistons from overtraveling. In conventional engines having crank shafts, pistons are attached Rigid mechanical stops are impractical in view of the fact that the pistons cannot be allowed to come into hard contact with a fixed stop since this would cause breakage of such members in many instances. the combustion end of the travel, the compression of the air in the combustion chamber is suilicient to prevent the pistons from coming into contact with each other and piston overtravel at the scavinging end of the stroke is controlled by cutting down the amount of fuel supplied to the combustion chamber whenever the pistons tend to overtravel. Referring to Fig. l, it will be seen that when pistons I5 and I6 are in their outward position the synchronizing racks 38 and 39 have moved cam 44 to a position where cam lobe |64 comes into contact with the plunger of valve |48 which may be termed an overtravel governor valve. Normally cam 4t does not move sufficiently far to open valve |48. Valve |49 is in conduit 5| connected to a source of fuel under pressure S, and when this valvev is opened by lobe |64 due to piston overtravel.

'fuel under pressure is transmitted to chamber |42 through conduit 5|, thereby moving piston |33 toward the left and consequently cutting down the capacity of discharge chamber 83.

Referring more particularly to Fig. 2, one form of valve |48 and its actuating mechanism are 4 disclosed. A housing |49 is attached to the tcp of body 18 by bolts, as shown. A vertical bore extends through body |49 within which a rod |5| is movable, the rod including a valve head |52 at its upper end for opening and closing a passageway between conduits |53 and 5i, conduit 5| being connected to chamber M2. Valve head |52 is held downwardly upon its seat by a spring |54 bearing against a cap |55 closing the top of the housing. The lower end of valve stein |5| bears against the adjusting screw oi a push rod |56, the push rod being slidable within a bore through body 15. A collar itil is held to the lower end of push rod |56 by means of a split retaining ring |59 and a spring is arranged to bear against collar |51 to hold the push rod in its lowermost position, an enlarged flange |59 forming part of the upper end of the push rod to determine the final position thereof. A rocker |6| is pivotally attached to body 15 on a shaft |62, one end thereof being provided with a semi-spherical bearing seat |63 to contact with a corresponding bearing at the lower end of pushvrod |56. The other 'end of the rocker arm is adapted to contact the abutment or lobe |54 associated with cam 4t. A torsional spring |55 surrounding shaft |62 has one of its ends held to rocker |6| and the other of its ends stationarily held whereby the rocker is biased tc continuously bear against the lower end of push rod |55.

In the position shown in Fig. 2, the synchroniz'ing racks 38 and 39 being in their scavenging or outward positions, the fuel injector valves are closed and if the pistons have not traveled beyond the permissible limit the valve |48 is 'also closed, that is, valve head |52 is on its seat. If, however, the pistons have overtraveled, lobe it@ on cam 44 has moved rocker arm iti and consequently has moved the push rod upwardly to lift valve head |52 off its seat. This allows an impulse of fuel to flow inwardly through conduit |53, through conduit 5| to chamber |52, thereby moving piston |33 (Fig. 5) to a position reducing the capacity of fuel discharge chamber 83. If the amount of overtravel is large, valve In the present invention, at

- ll Y head |52 is lifted farther off itsseat allowing a greater amount of fuel to flow into chamber |42, andconsequently moving piston |33 a greater distance away from its preset position, that is, closer toward the position of zero fuel capacity. Conversely, if the amount of overtravel is small, valve head |52 is lifted only a short distance oir its seat and only a small amount of fuel flows into chamber |42, and governor piston |33 is moved only a short distance away from its preset position. As soon as pistons and I6 move away from the scavenging end positions, that is, toward the combustion end, valve head |52 moves to its closed position under the influence of springs |54 and the fuel in chamber |42 is trapped there to hold piston |33 in its displaced position. Consequently, the amount of fuel supplied to the engine thereafter from chamber 83 is reduced and the travel of the pistons on the next combustion stroke is reduced by an amount proportional to the displacement of piston |33, i. e., proportional to the overtravel. The oil in chamber |42 is slowly forced out through adjustable needle valve |46 under the influence of spring |35. Thus, when the stroke of pistons |5 and I6 has once been cut down following their overtravel, the amount of fuel supplied to the engine is cut down for several succeeding strokes of the pistons until the oil within chamber |42 has leaked out. When this has occurred governor piston |33 will be in its normal preset position and the generator will be receiving the amount of fuel determined by the governor and indicated on scale |39.

The overtravel governor valve |48 and its operating mechanism including rocker |6| togeher with the governor mechanism 48 act as a regulating governor to hold the fuel at the desired throttle setting at higher generator speeds, even though overtravel occurs. Suppose the pressure of gas receiver 31 is high, i. e. high load. Then, the speed of the pistons and the synchronizing racks is high. Now, if piston overtravel occurs. the time valve head |52 is on its seat is small and only a small amount of fuel enters chamber |42. Consequently, only a small change in the position of piston |33 is made and the time for the piston to return to full fuel position is small. Hence *he overtravel is reduced in small amounts without sudden change in generator speed. On the other hand, if receiver 31 pressure is low, i. e. low generator load, the speed is low and, consequently, if piston overtravel occurs valve |52 is open longer with a resultant 1arger movement of piston |33. The capacity of metering chamber 83 is thus cut down further and a longer time is needed for it to return to the full value of the throttle setting. Thus, the return to full fuel setting is slower and the reduction in overtravel is faster at low loads than at high loads.

Presfre in the combustion chamber is a function o f the pressure in exhaust receiver 31 as well as the pressure in scavenging air receiver 21, since the compressed air in receiver 21 flows through the combusion chamber at the scavenging end of power pistons l5 and I6 and thereby determines the actual pressure of the air in cylinder 2 when the pistons begin the return stroke.

.Accordingly, with load variations, the pressure within the combustion chamber may vary, +hese following the variations in the pressure of receiver 31. Since it is desirable in internal combustion engines to produce combustion at a cerarsenaal tain point in the piston travel determined by the 16 12 load on the engine as well as other factors. the timing of the fuel injection is varied in accordance with the pressure in receiver 31, this being accomplished by connecting receiver 31 through the conduit 46 to the pressure responsive device 46.

Referring to Figs. 2 and 4, the pressure responsive mechanism 46 is associated with the left end of structure and comprises a base |86 and a regulator body |61, these two members being attached to each other and to the body 16 by bolts |68. Disposed centrally of body |61 there is a regulator shaft |69 at the lower end of which a circular diaphragm |1| is attached, the outer periphery of the diaphragm being clamped in fluid-tight relation to body |61 and base |66, and defining a chamber |12 connected to exhaust receiver 31 through conduit 46. A spring |13 bears against a collar on the lower end of shaft |69 and against an adjusting nut |14 at the upper end of body |61, the force of spring 13 being balanced against that of the pressure in chamber |12. The upper end of shaft |69 is forked and a lever |15 is disposed between the forks and pivoted thereto. One end of lever |15 is split and is attached to a link |16 by means of a swivel pin |11, the link |16 including a reduced portion at one end which is surrounded by a spring |18 on one side of swivel pin |11. On the other side of swivel pin |11, the link |16 is threaded and is provided with an adjusting nut |19. 'I'he other end of lever |15 is attached to a fulcrum link |8| pivoted to body |61 by a shaft |82, the other end of link |6| being split and pivoted to lever |15 by means of a swivel pin |83. On one side of pin |83 there is a spring |84, and on the other side there is an adjusting nut |85. Link 16 being connected to rack |32 as shown, adjusting nuts |19 and |85 may be positioned to adjust the p0- sition of the rack, which in turn shifts the relative rotational posiion of timing plunger 53 to a desired value which for normal pressure conditions within exhaust receiver 31 and for a particular load condition on the gas generator will produce proper timing of fuel injection.

When the generator is not operating, there is no pressure in chamber |12 and spring |13 positions rack 32 to its lowest position. When the generator is starting, the pressure in chamber |12 will .be low and consequently the position of rack 32 is maintained in its lowest position, as a result of which the fuel injection would occur when the pistons are closest to each other in the piston chamber, that is, the fuel injection would occur as late as possible in the cycle. As the pressure increases in exhaust receiver under increasing load conditions, the shaft |69 is moved upwardly against the bias of spring |13 thereby moving rack |32 and consequently shifting the rotational position of plunger 53 to eil'ect fuel injection earlier in the operating cycle. Referring to Fig. 1, it will be seen that as diaphragm |1| is forced upwardly, the rack |32 moves upwardly to rotate plunger 53 counterclockwise when viewing the left end thereof. thereby positioning slot ||9 so that it comes into communication with the conduits |08, ||1 sooner, or while pistons |5 and |6 still have a short distance to travel. When the pressure in exhaust receiver goes down, spring |13 returns the diaphragm to a lower position thereby reversely rotating plunger 53 to bring a portion of slot I9 into communication with conduit |88, ||1 at a latter point. The stiffness of spring |13 may be so chosen and the adjustment of nut |69 so made,

ananas;

together with positioning'of adjusting nuts |19 and |85', that the rotational'position of plunger 53 is correctJ for proper timing under a particular load condition, i. e., full load. In this case diaphragm |1| would occupy an intermediate position and consequently could move to compensate for pressure changes in receiver 31 requiring a greater travel of the plunger.

The pistons |5 and |76 being free pistons and being returned to the combustion position by air compressed in cylinders 23 and 25, there may be a tendency for one or both of the pistons to develop excessive friction or actually stick in their movements, thereby placing excessive strain on the moving parts unless the generator stops operating. As has already been described, when this condition occurs the assembly 6| moves laterally and actuates a safety valve 12 to supply fuel to chamber |42 of the governor in suiiicient pressure and in sufficient amount to shift cylinder |33 to a position of zero fuel capacity. Consequently the generator stops operating.

Referring to Fig. 2, valve 12 comprises a body |86 attached to abutment 69. The body |86 includes a central bore in which a plunger |81 is movable, the plunger including a valve head |88 cooperating with a valve seat to open and close a passageway from conduit 52 to conduit |9|, which is connected to the source of fuel under pressure. Associated with body |86 is a trip lever |92 having three portions and pivoted on a shaft |93, one of the portions being provided with an adjusting screw |94 abutting the housing 6-6. An adjusting screw |95 cooperating with a manual reset button |96 is threaded to another portion of the trip lever, and the third portion thereof abuts against the valve plunger |81. In the normal position of the safety valve parts, adjusting screw |94 abuts housing 66, -adjusting screw |95 holds manual reset button |96 outwardly against the bias of spring 91, and valve head |88 is maintained on its seat by a spring |98. In this position there is no fuel flowing from conduit |9| to conduit 52 and the operation of the generator is unaffected.

If. however, one oi.' the generator pistons should tend to stick or develop excessive-friction, the

, assembly 6| moves against the bias of spring 66 and the trip lever |92 forces valve plunger |81 down to allow fuel under pressure to flow from conduit |9| to chamber |42. |92 is pivoted a very small amount by a very small movement of assembly 6|, the adjusting screw |95 is moved sufficiently so that spring |91 moves manual reset button |96 into a position blocking the return of trip lever |92 to normal. Hence fuel under pressure is continually exerted against the base of piston |33 thereby maintaining a shutoff fuel condition until an attendant comes and pulls the manual reset button |96 outwardly to allow spring |98 to return the valve plunger |91 to its normal position.

Thus, during the operation of the gas generator, the injection of fuel, the timing of the fuel injections, the regulation of the governor to account for overtravel of the free pistons, and the stopping of the generator in the event that the pistons develop excessive friction are automatically taken account of.

While a, particular embodiment of the invention has been shown, it will be understood, of course, that the invention is not limited thereto since many modifications may be made, and it is, therefore, contemplated by the appended claims When the trip lever 14 to cover any such modifications as fall within the true spirit and scope of the invention.

Having thus described the invention what is claimed and desired to be securedvby Letters Patent is:

1. Gas generating apparatus comprising a motor cylinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder, a pair of free .pistons each including a motor piston portion and a compressor piston portion movable between combustion and scavenging positions, each of said free pistons being arranged with the compressor piston portion thereofin a compressor cylinder and with the motor piston portions thereof facing each other in said motor cylinder and defining a combustion chamber for supplying gas under pressure, means for synchronizing the movement of said pistons, means for returning said pistons from scavenging positions to combustion positions, a receiver for the combustion gases, injection means operative when said pistons are at combustion position for injecting fuel into said combustion chamber, means responsive to the pressure in said receiver for varying the timing of said fuel injection, governing means for determining the amount of fuel injected by said injection means. and means responsive to the position of said pistons at the scavenging end of piston movement for varying the amount of fuel determined by said governing means.

2. Gas generating apparatus comprising a combustion chamber for supplying gases under pressure, a chamber for receiving the gases from said combustion chamber, fuel pressure operated means for injecting measured amounts of fuel into said combustion chamber, means for initiating operation of said injecting means, means responsive to the pressure in said gas receiving chamber for varying the timing of said initiation, governing means for determining said measured amount of fuel, and means .responsive to a condition of the generating apparatus operation for altering the amount of fuel determined by said governing means.

3. Gas generating apparatus comprising a combustion chamber for supplying gas under pressure, a chamber for receiving the gas from said combustion chamber, a fuel measuring chamber, a piston movable in said chamber under the influence of fuel under pressure for injecting the fue] in said measuring chamber into said combustion chamber, valve means having differential areas exposed to said fuel pressure for preventing ejection of fuel from said measuring chamber, timing means controlled by said generating apparatus for relieving the fuel pressure from one of said differential areas whereby said valve means open and said piston moves to produce fuel injection, means responsive to the pressure in said gas receiving chamber for varying the timing. of said fuel injection, governing means for determining the capacity of said fuel measuring chamber, and means responsive to a change in piston stroke for altering the fuel measuring chamber capacity determined by said governing means.

4. Gas generating apparatus comprising a combustion chamber for supplying gas under pressure, a fuel measuring chamber, a piston movable therein under the influence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, means controlled by said generating apparatus for timing said fuel injection, governing means for deter.

arsenaal' mining the initial position of said piston in said measuring chamber for determining the volume of fuel ejected therefrom, fluid pressure responsive means for altering said initial piston position, and means responsive to a stroke of said gas generating apparatus for supplying fluid under pressure to said uid pressure responsive means.

5. Gas generating apparatus operating with periodic injections of measured amounts of fuel comprising a combustion chamber for supplying gas under pressure, a fuel measuring chamber, an injection piston movable in said measuring chamber under the influence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, means controlled by said generating apparatus for timing said fuel injection. governing means for determining the initial position of said injection piston in said measuring chamber for determining the volume of fuel ejected therefrom, said governing means including a governing chamber and a governing piston therein biased to main-y tain the initial position of said injecting piston and being movable in one direction in said governing chamber for altering the initial position of said injecting piston, means responsive to a condition of said generating apparatus operation for supplying a pulse of fluid under pressure to said governing chamber thereby to move said governing piston in said one direction against its bias, and bleeding means associated with said governing chamber whereby said pulse of fluid is forced out of said governing chamber by said governing piston and its bias and said governingpiston returns to its initial position.

6. Gas generating apparatus comprising a combustion chamber for supplying gas under pressure, a fuel measuring chamber, a piston movable therein under the inuence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, means controlled by said generating apparatus for timing said fuel injection. governing means for determ'ning the initial position of said piston in said measuring chamber for determining the volume of fuel ejected therefrom, uid pressure responsive means having an initial position and being movable to alter said initial position, means responsive to a condition of said gas generating apparatus for supplying a, pulse of fluid under pressure to said fluid pressure responsive means, and means for bleeding away the fluid of said pulse whereby said uid pressure responsive means returns to its initial position.

7. Gas generating apparatus operating with periodic injections of measured amounts of fuel comprising a combustion chamber for supplying gas under pressure, a chamber for receiving the gas from said combustion chamber, a fuel measuring chamber, an injection piston movable therein under the influence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, valve means having differential areas exposed to said fuel under pressure for preventing ejection of fuel from said measuring chamber, timing means controlled by said generating apparatus for relieving the fuel pressure from one of said differential areas whereby said valve means opens and said injecting piston moves to produce said fuel injection, means responsive to the pressure in said gas receiving chamber for varying the timing of said pressure relieving means, governing means `for determining the initial position of said injec- 16 tion piston in said measuring chamber for determining the volume of fuel ejected therefrom, said governing means including a governing chamber and a governing piston therein biased to maintain the initial position of said injection piston and movable in one direction for altering the initial position of said injecting piston. means responsive to a condition of said generating apparatus for supplying a pulse of fluid under pressure to said governing chamber thereby to move said governing piston in said one direction against its bias, and bleeding means associated with said governing chamber whereby said pulse of fluid is forced out of said governing chamber by said governing piston and its bias.

8. Gas generating apparatus comprising a motor'cylinder, a compressor cylinder at one end thereof, a, free piston including a motor piston portion in said motor cylinder defining a combustion chamber for supplying gas under pressure and a compressor piston portion in said compressor cylinder, said free piston being movable between combustion and scavenging positions, means for returning said piston from scavenging position to combustion position, a receiver for said gas from said combustion chamber, injection means operative when said piston is at combustion position for injecting fuel into said combustion chamber, means responsive to the'pressure in said receiver for varying the tim- .ing of fuel injection by said injection means, governing means for determining the amount of fuel injected by said injection means, and means responsive to the position of said piston at the scavenging end of piston movement for varying the amount of fuel determined by said governing means.

9. Gas generating apparatus comprising a motor cvlinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder, a pair of free pistons movable between combustion position and scavenging positions. each piston including a motor piston portion in said motor cylinder and a compresor piston portion in respective compressor cylinders, said motor piston portions facing each oher and forming a combustion chamber for supplying gas under pressure, means for synchronizing movement of said pistons, a receiver for the gases from said combution chamber, a fuel measuring chamber, an injec ion pi'zton movable therein under the influence of fuel under pressure for injecting the fuel in said measuring chamber into said cornbustion chamber, valve means having differential areas exposed to said fuel under pressure for preventing ejecfion of fuel from said measuring chamber, timing means controlled by said apparatus when said pistons are at combustion position for relieving the fuel pressure from one of said differential areas vfhereby said valve 'means lopers and sai'i injecting piston moves to produce said fuel injection, and means responsive to the pressure in lsaid receiver for varying the timing of said pr-.fssure rali-ving means.

l0. Gas generafing apparatus comprising a motor cylinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder, a pair of free pistons movable between comburtion position and scavenging positions, each piston including a motor piston portion in said motor cylinder and a compressor piston portion in respective comprestor cylinders, said motor pis'on portions facing each other and forming a combustion chamber for supplying gas under pressure, means for synchronizing movement I Maasai of said pistons, a receiver for the gases from said combustion chamber. a fuel measuring chamber. an vinjection piston movable therein under the inuence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, valve means having differential areas exposed to said fuel under pressure for preventing ejection of fuel from said measuring chamber. timing means controlled by said apparatus when said pistons are at combustion position for relieving the fuel pressure from one of said dierential areas whereby said valve means opens and said injecting piston moves to produce said fuel injection. and means responsive to the pressure in said receiver for varying the timing of said pressure relieving means, governing means for determining'the initial capacity of said fuel measuring chamber, and means responsive to the position of said pistons at the scavenging end of piston travel for altering said initial fuel measuring chamber capacity. il. Gas generating apparatus comprising a motor cylinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder, a pair of free pistons movable between combustion and scavenging positions, each piston including a motor piston portion in said motor cylinder and a compressor piston por- 1tion in respective compressor cylinders, said motor piston portions facing each other and forming a combustion chamber, means for synchronizing movement of said pistons, a fuel measuring chamber, an injecting piston movable therein under `the influence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, timing means controlled by said generating apparatus when said pistons are at combustion position for effecting said fuel injection, governing means determining the initial position of said injecting piston in said measuring chamber for determining the volume of fuel ejected therefrom, fluid pressure responsive means for altering said initial piston position, and means responsive to the position of said free pistons at the scavenging end of piston travel for supplying fluid pressure to said fluid pressure responsive means.

l2. Gas generating apparatus comprising a] motor cylinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder, a pair of free pistons movable between combustion and scavenging positions, each piston including a motor piston portion in said motor cylinder and a compressor piston portion in respective `compressor cylinders, said motor piston portions facing each other and forming a combustion chamber, means for synchronizing movement of said pistons, a fuel measuring chamber, an injecting piston movablel therein under the influence of fuel under pressureQfm` injecting the fuel in said measuring chamber into said combustion chamber, timing means controlled by said generating apparatus when vsaid pistons are at combustion position for effecting said fuel injection, governing means determining the initial position of said injecting piston in said measuring chamber for determining the volume of fuel ejected therefrom, said governing means including a governing chamber and a governing piston therein biased to maintain the initial position of said injecting piston and movable in one direction in said governing chamber for altering the initial position 'of said injecting piston, means responsive to the position of Said free pistons at the `motor cylinder, a pair of free pistons movable between combustion and scavenging positions, each piston including a motor piston portion in said motor cylinder and a compressor piston portion in respective compressor cylinders, said motor piston portions facing each other and forming a combustion chamber, means for synchronizing movement of said pistons, a. fuel measuring chamber, an injecting piston movable therein under the influence of fuel under pressure for injecting the fuel in said measuring chamber into' said combustion chamber, timing means controlled by said generating apparatus when said pistons are at combustion position for eil'ecting said fuel injection, governing means determining the initial position of said injecting piston in said measurng chamber for determining the volume of fuel ejected therefrom, fluid pressure responsive means having an initial position corresponding to said injecting piston initial position and being movable to alter said injecting piston initial position, means responsive to the position of said free pistons at the scavenging end of piston travel for supplying a pulse of fluid under pressure to said fluid pressureresponsive means, and means for bleeding away the fluid of said pulse whereby said fluid pressure responsive means returns to its initial position.

14. Gas generating apparatus comprising a motor cylinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder, a pair of free pistons movable between combustion position and scavenging positions, each piston including a motor piston portion in said motor cylinder and a compressor piston portion in respective compressor cylinders, said motor piston portions facing each other and forming a combustion chamber for supplying gas under pressure, a receiver for the gases from said combustion chamber, a fuel measuring chamber, an injection piston movable therein under the influence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, valve means having differential areas exposed to said fuel under pressure for preventing ejection of fuel from said measuring chamber, timing means controlled by said apparatus when said pistons are at combustion position for relieving the fuel pressure from one of said differential areas whereby said valve means opens and said injecting piston moves t0 produce said fuel injection, and means responsive to the pressure in said receiver for varying the timing of said pressure relieving means, governing means determining the initial position of said injecting piston in said measuring chamber for determining the volume of the fuel ejected therefrom, said governing means including a governor chamber and a governing piston therein biased to maintain the initial position of said injecting piston and movable in one direction for altering the initial position of said injecting piston to decrease the volume of fuel ejected from f, 19 said measuring chamber, valve means controlled bythe overtravel of said free pistons at the scavenging end of piston travel for supplyln a pulse oi.' fluid under pressure to said governing chamber thereby to move said governing piston in said one direction against its bias. and bleeding means associated with said governing chamber wherebyl said pulse of fluid is forced out of said governing chamber by said governing piston and its bias. l

15. Gas generating apparatus comprising a motor cylinder, a pair of compressor cylinders respectively disposed at opposite ends of said motor cylinder. a pair'of free pistons movable between combustion and scavenging positions. each piston including a motor piston portion in said motor cylinder and a. compressor piston portion in respective compressor cylinders, said motor piston portions facing each other and forming a combustion chamber, means for synchronizing movement of said pistons. an injecting piston movable therein under the influence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber. timing means controlled by said generating apparatus when said pistons are at combustion position for effecting said fuel injection, governing means determining the initial position of said injecting piston in said measuring chamber for determining the fuel capacity thereof, said governing means including a governing chamber and a governing piston therein, said governing piston being biased to maintain the initial position of said injecting piston and being movable in one direction for altering the initial position of said injecting piston to decrease the capacity of said measuring chamber, and means responsive to non-synchronism tendencies of said free pistons for supplying fluid pressure to said governor chamber thereby to move said governing piston to effect reduction of said measuring chamber capacity of substantially zero.

16. Gas generating apparatus comprising a motor cylinder, a pair of compressor cylinders respectively at opposite ends of said motor cylinder. a pair of free pistons movable between combustion position and scavenging positions, each piston including a motor piston portion in said motor cylinder and a compressor piston portion in respective compressor cylinders, said motor piston portions facings each other and forming a combustion chamber for supplying gas under pressure, a receiver for the gases from said combustion chamber, a fuel measuring chamber, an

20 at the combustion end, said timing valve plunger including a longitudinally angular slot for relieving the fuel pressure from one of said diil'erfential areas at said plunger operation thereby to effect opening of said valve means to produce fuel injection, means responsive to the pressure in said receiver for rotating said plunger for varying the timing of said pressure relief, governing means for determiningthe initial capacity of said fuel measuring chamber. and means responsive to the position of said free pistons at the scavenging end of piston travel for altering said initial injection piston movable therein under the inuence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, valve means having differential areas exposed to said fuel under pressure for preventing ejection of fuel from said measuring chamber, a timing valve plunger operated by said generating apparatus when said free pistons are fuel measuring chamber capacity.

17. Gas generating apparatus comprising a motor cylinder. a pair of compressor cylinders disposed respectively at opposite ends of said motor cylinder, a pair of free pistons movable between combustion position and scavenging positions, each piston including a motor'piston portion in said motor cylinder and a compressor piston portion in respective compressor cylinders, said motor piston portions facing each other and forming a combustion chamber for supplying gas under pressure, a receiver for the gases from said combustion chamber, a fuel measuring chamber, an injection piston movable therein under the iniluence of fuel under pressure for injecting the fuel in said measuring chamber into said combustion chamber, valve means having differential areas exposed to said fuel under pressure for preventing ejection of fuel from said measuring chamber, a timing valve plunger operated by said generating apparatus, said timing valve plunger including a. longitudinally angular slot for relieving the fuel pressure from one of said differential areas thereby to effect opening of said valve means to produce fuel injection, diaphragm means movable in response to the pressure in said receiver for rotating said plunger for varying the timing of said pressure relief, governing means for determining the initial capacity of said fuel measuring chamber, and means responsive to overtravel of said free pistons at the scavenging end of piston travel for reducing said initial fuel measuring chamber capacity.

LOUIS J. GARDAY.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 2,182,063 Steiner Dec. 5. 1939 2,200,892 Pateras Pescara May 14, 1940 2,355,177 Pateras Pescara Aug. 8, 1944 2,425,850 Welsh Aug. 19. 1947 2,426,297 Cooper Aug. 26, 1947 FOREIGN PATENTS Number Country Date 551,519 Great Britain. of 1943 Patent No. 2,531,331

Certificate of Correction November 21, 1950 LOUIS J. GARDAY -It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, lines 44 and 45, after the word measuringV insert chamber; column 2, lines 6 and 7, after invention" insert is; column 3, lines 56 and 57, strike out amount of `fuel supplied to the engine thereby reducing the, column 4, line 59, for piston read pistons; column 7 line 2, strike out the numeral 119, column 8, line 70, s trike out an; line 73, for needle body 41 read needle body 141; column 9, line 17, for ito read into; column 12, line 74, for latter read later;

and that the said Letters Patent shouldbe read as corrected above, so that the same may conform to the record of the case in the Patent Oiice.

Signed and sealed this 6th day of March, A.. D, 1951.

THOMAS F. MURPHY, v

Assistant Commissioner of Patents. 

